The present invention relates to a proximity switch for detecting the approach of objects of metallic material, of the type disclosed in EP 340 660 A2 and DE-A 37 21 127.
In the known proximity switches, an oscillating circuit is provided which includes a coil, and which is connected to a source of constant voltage. The electromagnetic damping of the coil is determined, and more particularly, the adjacent position and/or state of motion of the metallic object is signalled by detecting and evaluating the voltage drop which occurs across an internal sensing resistor which is connected to the oscillating circuit.
It is the object of the invention to increase the response time and sensitivity of the proximity switch of the described type.